AV Node Velocity — FRCA Primary MCQ
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Correct answer: B — 0.05 m/s
The best answer is B: approximately 0.05 m/s. AV nodal tissue conducts much more slowly than the other components of the cardiac conduction system; experimental measurements vary with the preparation and pacing rate but remain of the order of 0.05–0.1 m/s. Slow conduction reflects small nodal cells, relatively sparse electrical coupling and a slow-response action-potential upstroke mediated predominantly by L-type calcium current rather than fast sodium current. This contributes to atrioventricular delay, although delay at the atrial–nodal interface is also important. A velocity of 0.5 m/s is more typical of working atrial or ventricular myocardium. Values around 1–4 m/s describe the rapidly conducting His–Purkinje system rather than the AV node.
Reference: Choi BR, Ziv O, Salama G. Conduction delays across the specialized conduction system of the heart: Revisiting atrioventricular node (AVN) and Purkinje-ventricular junction (PVJ) delays. Front Cardiovasc Med. 2023;10:1158480. https://pubmed.ncbi.nlm.nih.gov/37153461/